Fabia 2001 ATD Cambelt Change

[Ricardo vRS]

I'm considering changing my own cambelt on my 2001 ATD and have found a tech guide on the vRS cambelt change very informative. I have a question though about the cam sproket. Why is it necessary to undo it and put the bolts in the centre of the holes. Surely they should already be in the centre? Why can't you just take the old belt off the sproket and put the new one on with the sproket remaining in the same place? I'm sure I'm missing something obvious but I can't think why you need to do this.

Is the tech guide for the vRS an appropriate guide for me to use for an ATD?

Any advise greatfully received!

Thanks

Steve

[dj_max]

according to ETKA, timing belt or the whole timing set (+tensioner) are exactly same so the tech guide for vrs is ok to use for ATD.

cam sprocket is screwed to hub which is rotating camshaft so if cam sprocket is loose it can rotate but hub and camshaft stays in same possition

while putting new belt on and setting the tensioner you may actualy put so much presure on belt that it will be able to rotate the camshaft if screws are not loose.

[Ricardo vRS]

... but the cam shaft is locked in position with the pin, so it can't rotate. Thus my confusion regarding the need to loosen the cam sprocket. On every other car I've done, I've never loosened the cam sprocket. I just mark the cam and crank up, take the old one off and put the new one on, ensuring the cam and crank are in the same original position.

Please help clarify this one!

Thanks

[dj_max]

cam shaft is locked in position until you remove the pin

when you put cam belt on there may be more tension on one side of the crank than on the other side and when you remove pin it will rotate cam shaft a little bit.

it is only a little bit but the timing may change slightly and you may for example loose power (you may even not notice it) or in extreme case cylinder may hit the valve or valves

(even slightly hitting corner of valve may cause it to crack and even if valve is still tight the cracked piece will fall into chamber causing scratches to the side of it and then you may need new cylinder head)

there is of course minimal tolerance so you may be lucky and without loosing the cam sprocket everything will be fine and that's probably what happened with your previous changes..

also one more thing is that brand new cambelt is slightly shorter than one that did eg 60k miles (that's tensioner's job to adjust the changes during cambelt's lifetime)

and if you put it on, the possiton of the crank will change (rotate few degrees) that's why you should loose the screws to adjust this difference.

it is your choice and if you did that succesfully before you may be lucky this time as well but i advice you to follow the instuction and loose these screws.

[Ricardo vRS]

O.K. - Thanks - I've got it now!

Strange that other cars I've worked on (Cavaliers etc) didn't have ovulated holes holding the cam sprocket on, so you couldn't do this. I suppose this method ensures a very precise timing set up.

I'll give it a go.

Thanks for your help

PS - Can you buy a tool to hold the sproket in place whilst undoing the bolts, or do most people just make one themselves?